User equipment has advanced so as to perform multiple functions such as communicating voice and data with others; exchanging text messages or multimedia messages; sending e-mails; capturing a still or moving image; playing back a music or a video file, playing a game, and a receiving a broadcast signal. Lately, such multi-functional user equipment has received greater attention for new applications. Instead of using multiple independent devices, a user prefers to use single multifunction-enabled user equipment. Portability and/or mobility should be considered in design of user equipment, but such user equipment has limitations in size. Accordingly, there also are limitations in display screen size, screen resolution, and speaker performance.
In order to overcome such limitations, an external device having a large display size, better speaker performance, and connectable to a mobile terminal has been introduced. Such external device connected to the mobile terminal can provide data, music files, and other content stored in the mobile terminal in better performance.
For example, user equipment may be coupled to an external device having a large sized screen such as a TV or a projector and display image data through the external device. In this case, the external device displays mirrored image data that is exactly same as image data displayed on user equipment. Due to such a typical way of transferring image data from the user equipment to the coupled external device, a user might not desire to show all image data produced in the user equipment on the external device. For example, while displaying a presentation material on a larger screen TV coupled to the user equipment, a user might receive a text message from other party. When such text message has very private content, a corresponding user might be very embarrassed and audiences thereof might be greatly distracted.